The gross vehicle weight of tractor-trailer combinations is, conventionally, limited by the weight that can be placed on the fifth-wheel coupling on the tractor, which coupling is normally mounted to the truck frame. The load placed on the fifth-wheel coupling is generally balanced between the front and rear of the tractor.
The applicant is aware of U.S. Reissue Pat. No. 23,704, which reissued on Sep. 1, 1953 to Manford S. De Lay for a "Load Equalizing Device". DeLay teaches a fifth-wheel coupling mounted on a translatable carriage for translation longitudinally along the longitudinal members of a tractor frame. The carriage is secured at desired positions along the tractor frame by actuable pins extending from the carriage and journalled in holes in the longitudinal frame members. The De Lay device is known in the art as a fifth-wheel slider.
The applicant is also aware of U.S. Pat. No. 3,493,935 which issued on Apr. 22, 1969 to W. W. Guidice for a "Fifth Wheel Tractor" device. Guidice discloses a subframe pneumatically mounted at its ends onto a tractor frame, the fifth wheel coupling point being adjustable longitudinally by translation of the fifth wheel kingpin. Limited weight transfer between the forward and rearward wheels of the tractor is accomplished by tilting of the subframe on its pneumatic mounts.
The present invention provides a subframe weight transfer device to apportion to the front wheels of a tandem steer tractor some of the load otherwise transferred to the rear wheels of the tractor by the fifth-wheel coupling or like load transfer coupling device. It is a further object of this invention to thus allow for an increase in gross tractor-trailer vehicle weight, that is, including trailer load, by increasing the load bearing capacity of the tractor transferred to the tractor by a fifth-wheel coupling or like load transfer coupling device, while maintaining the requisite tractor weight balance and minimizing the over all increase in vehicle tare weight.